Conventionally, electronics cabinets such as those with rack mounted electronics, such as circuit boards and connectors, are cooled by directing cooled air vertically up through the cabinet. The cooled air typically enters the cabinet at or near the floor and the heated air exits at or near the top of the cabinet. Circuit boards are arranged vertically such that air flows bottom to top along the surfaces of the circuit boards, taking advantage of the fact that hot air rises. Electrical and optical connectors are sometimes cooled by such airflow, depending on the configuration.
Cabinets including electronics that are cooled in this manner exhibit a significant caloric rise from bottom to top as the circulated air heats draws heat from each of the electronics in its path. Notably, the distance the air travels vertically through a tall cabinet significantly reduces the cooling efficiency of the upper electronics. Moreover, the cooling efficiency drops further due to the pressure drop from the bottom to the top of the cabinet.
In addition, such a cooling approach is often complex and expensive. Air conditioning may be needed to cool the air before it enters the cabinet. If the heat rise of the circulated air up through the cabinet is large, intercooler assemblies may be placed between electronics assemblies to extract heat from the vertically directed air between each assembly. Intercooler assemblies sometimes include a refrigerant or a liquid such as water to aid in extracting heat from the air passing through the intercooler assembly. Such approaches increase the heat generated by the cabinet, further reducing the power usage efficiency (PUE) of the unit.
Connectors, including backplane connectors interfacing electrical and optical signals into a card cage assembly including the circuit boards, also generate a significant source of heat during operation. Both wired and optical connectors can generate between 2 to 10 Watts of heat each in some configurations, which cumulative heat significantly increases the temperature within the cabinets and also the ambient. This heat generated by the connectors is not typically efficiently cooled or expelled from the cabinet because the connectors are not located in the cooling envelope of the air flow. While air flow may be provided across the circuit boards, the connectors extending through the backplanes interfacing with the circuit boards significantly extend behind the backplane and the card cage assembly, and may generate heat in a space or cavity defined between the backplane and the cabinet rear wall, or are exposed to the ambient.
What is needed is a system and method that addresses these issues and other issues that will become apparent in reading below.